Generally, laptop computers are designed with a connector, through which an external storage device such as FD drive and CD-ROM drive can be removably connected. In many cases, such laptop computers are also equipped with a rechargeable battery (i.e., a battery pack) for use as a power source. Therefore, the laptop computers need a connector with a plurality of electrical contacts, which is to be used for signal transmission with an external device, and a connector with electrical contacts for power transmission which require a larger capacity than those used for signal transmission, to allow current flow.
There is a yet sophisticated design of laptop computer which houses an attachment, i.e, an external device, a battery pack, etc. in the main body of the laptop computer. There is such type of laptop computer which enables alternative or exchangeable connection of an attachment, instead of allowing a plurality of attachments to be housed in the main body. In this way, the size of the laptop computer can be minimized for portability. In this design, each attachment is constructed with the same outside dimensions, and a receptive space for the insertion of an attachment is provided in the main body of the computer. A connector is provided in this receptive space to enable the removable connection of the attachment to the computer, such that the user can operate the laptop computer comfortably with a right attachment for his current need just by inserting or exchanging the attachment accordingly.
Such attachments include an external memory device, which does not require contacts for power transmission, and a battery pack, which requires electrical contacts that allow current flow. When the laptop computer is constructed in the above mentioned design to enable exchangeable insertion of attachment devices, electrical connectors, one connector for signal transmission and the other for power transmission (e.g., in two rows, one above the other), are provided at different locations in the receptive space.
Lately, the laptop computers have undergone further miniaturization, and it is becoming difficult to provide a plurality of electrical connectors in the receptive space. This has lead to a design of universal electrical connector, in which a single connector provided in the receptive space of the laptop computer is used both as signal connector and power connector, thus enabling the removable and exchangeable connection of an attachment in accordance with the present need. However, the electrical contacts of this type of connector are arranged in a special way. For example, two electrical contacts for power transmission are provided at the lateral ends of a row of electrical contacts for signal transmission.
In this type of connector, the single design of connector is used commonly for various attachments, even the attachments which do not require power supply are equipped with electrical contacts designed for power transmission. As far as the cost of the connector is concerned, it is unwise to provide such unnecessary contacts, and it is also disadvantageous in pricing the attachments.